The present invention relates to the field of devices for the sterilization of contact lenses, and more specifically relates to the field of modern contact lens sterilization devices which incorporate within them means for providing heat for boiling and sterilization of such contact lenses.
Nowadays the use of contact lenses for eyesight enhancement and correction is becoming more and more popular, in line with increased demands for facial attractiveness and convenience of use. Especially in the case of so called soft type contact lenses, boiling and sterilization of contact lenses is very important from the point of view of ensuring comfortable use of said contact lenses, and from the point of view of preventing eye infections and eye irritation syndromes such as conjunctivitis and the like. Therefore, various types of contact lens sterilization device have been developed.
In a typical such contact lens sterilization device, there are included a lens storage casing formed with two lens storage compartments for storing the two contact lenses of a pair as each immersed in water or sterilization liquid, and a main body casing, formed separately from said leans storage casing, for accommodating a circuit unit and a heating means which is provided with energy for heating by said circuit unit. And the lens storage casing is mounted to the main body casing, so that the lens storage compartments should be supplied with heat generated by the heating unit under the control of said circuit unit, so as to heat and boil the water or sterilization liquid and the contact lenses contained in said compartments, thereby to sterilize said contact lenses. It is typical to form said lens storage casing separately from said main body casing, because there is a tendency for the water or sterilization liquid to overflow when it is being poured by the user into said contact lens sterilization compartments, and, since the main casing accommodates the circuit unit, said main casing is absolutely required to be proof against the intrusion of dirt or water or other moisture into it. In more detail, typically the heating unit comprises a heat emission plate to which a heating element is attached for heating it, and the heat produced by said heating element is conducted by way of the main body casing and the lens storage casing to the lens storage compartments and to the water or sterilization liquid and the contact lenses contained in said compartments, thereby to sterilize said contact lenses. This is typically done by such a heat emission plate construction as outlined above being typically held to the casing so that its one surface is wholly in contact with said casing, and the parts of said casing in the general vicinities of the lens storage compartments are heated up so as thereby to heat up said lens storage compartments.
However, since two separate casings are required in such a prior art contact lens sterilization device, the device has an undesirable tendency to become large in size and heavy. Nowadays, it it becoming very common for such a contact lens sterilization device to be carried by the user on his or her person, during trips or to work or the like, and according to such peripatetic use such bulkiness and such heaviness are great drawbacks.
Further, such a heat emission plate construction as outlined above is subject to the problems that, since the heat produced thereby is diffused via the casing to the lens storage compartments, much of the heat is conducted to irrelevant parts of the contact lens sterilization device and is wasted, thus entailing the disadvantages of low heating efficiency and large power consumption. Further, since various parts of the surface of the casing become unduly hot, a substantial risk is engendered of the user being burnt, scorched or scalded by touching said casing surface parts. In particular, although in a conventional type of contact lens sterilization device in which the lens storage casing comprising the contact lens storage compartments and the main body casing containing the heating device are provided as separate bodies there may be no substantial problem of the whole of the lens storage casing becoming unduly hot, in the case that these lens storage casing and main body casing are formed as one integral casing there is a great danger that the whole of the outer surface of the casing may become unduly hot. And, in the prior art, there has been no means provided of protecting the user against such heating up of the casing surface. Typically, if the lens storage chambers for sterilization of the contact lenses become heated up to temperatures of for example greater than 80.degree. C., then although parts of the casing of the contact lens sterilization device may become unduly hot the user is not made aware of this fact, which can cause severe problems, and the risk of burning, scorching, or scalding of said user is increased. And these problems are accentuated as the size of the contact lens sterilization device is reduced.